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GCSE Biology > Topic 5a - The Nervous System > Flashcards

Topic 5a - The Nervous System Flashcards

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1
Q

What is homeostasis?

A

Homeostasis is the regulation of conditions inside your body (and cells) to maintain a stable internal environment, in response to changes in both external and internal conditions.

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2
Q

Why is homeostasis important?

A

Because your cells need the right conditions to function properly, including the right conditions for enzyme action.

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3
Q

What do control systems do?

A

We have lots of automatic control systems in our bodies that regulate our internal environment, including both nervous and hormonal (chemical) systems. These happen unconsciously, usually involving the brain stem and the spinal cord.

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4
Q

What are the conditions in your internal environment that need regulating? (3)

A
  • Body temperature
  • Blood glucose
  • Water content of the body
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5
Q

What are control systems made up of? (3 with one overview bullet point)

A
  • 3 main components which work together to maintain a steady condition.
  • Cells called receptors
  • Coordination centres
  • Effectors
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6
Q

Where are the 3 coordination centres?

A
  • The brain
  • Spinal cord
  • Pancreas
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7
Q

What are 2 effectors?

A
  • Muscles
  • Glands
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8
Q

What is a stimulus?

A

A change in your environment that you might need to respond to is called a stimulus. A stimulus can be light, sound, touch, pressure, pain, change in position or temperature.

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9
Q

How do the 3 components of automatic control systems work/ what is the process?

A
  • Receptors detect a stimulus, which is a change in the environment.
  • Coordination centres receive information from the receptors, process the information and instigate a response.
  • Effectors create the response. Glands often release a hormone, which would restore the optimum condition.
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10
Q

What is the mechanism that restores the optimum level in an automatic control system called?

A

A negative feedback mechanism.

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11
Q

How long does the automatic control system process happen for? What does this mean/ how is it dealt with? (3)

A
  • Effectors carry on producing the responses for as long as they’re stimulated by coordination centre.
  • Might cause opposite problem of making the levels change too much (away from the ideal).
  • Receptors detect if level becomes too different and negative feedback starts again, so level kept at optimum.
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12
Q

What is significant about a multi-cellular organism responding to stimuli?

A

The cells of multicellular organisms need to communicate with each other before responding to the stimuli. Therefore they evolved to develop nervous and hormonal communication systems.

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13
Q

What are nerve cells called?

A

Neurones

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14
Q

What is a bundle of neurones called?

A

A nerve

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15
Q

What is the central nervous system?

A

The CNS is where all the information from the receptors is sent, and where reflexes and actions are coordinated.

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16
Q

What does the CNS consist of in vertebrates? (2)

A
  • The brain
  • The spinal cord
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17
Q

What does the peripheral nervous system contain? (PNS)

A
  • Nerves
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18
Q

How is the CNS connected to the body in mammals?

A

By sensory and motor neurones.

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19
Q

What are neurones made up of? (2)

A
  • Cell body => containing nucleus and main organelles
  • Cytoplasmic extensions from this body called axons and dendrites
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20
Q

How do neurones carry information very quickly?

A

In the form of electrical signals called nerve impulses.

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21
Q

How are neurones adapted in regards to size? Why? (2)

A
  • Some human neurones have axons over 1m in length, but only 1 - 4 Nm wide.
  • This is far more efficient than having multiple neurones to convey information from the CNS to effectors => less time wasted transferring electrical impulses from one cell to another.
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22
Q

How are axons adapted/ how do they work/ what do they look like?

A

The axon is insulated by a fatty myelin sheath with small uninsulated sections along it (nodes) which the impulses ‘jump along’.

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23
Q

What are the 3 types of neurone?

A
  • Sensory neurones
  • Relay neurones
  • Motor neurones
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24
Q

What are sensory neurones?

A

The neurones that carry information as electrical impulses from the receptors in the sense organs to the central nervous system.

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25
Q

What are relay neurones?

A

The neurones that carry electrical impulses from sensory neurones to motor neurones. Found in CNS.

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26
Q

What are motor neurones?

A

The neurones that carry electrical impulses from the central nervous system to the effectors.

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27
Q

What are 3 examples of effectors producing a specific response to a detected stimulus?

A
  • Muscle contracting to move an arm.
  • Muscle squeezing saliva from salivary gland.
  • Gland releasing a hormone into blood.
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28
Q

What is a reflex?

A

Reflexes are fast, automatic responses to certain stimuli. They bypass your conscious brain completely when a quick response is essential => reduce risk of being injured, among other things.

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29
Q

What general sequence does a reflex action follow? (8)

A
  • Stimulus
  • Receptor
  • Sensory neurone
  • Relay neurone (in CNS)
  • Coordinator/ coordination centre
  • Relay neurone
  • Motor neurone
  • Effector
  • Response
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30
Q

What is the more detailed 5 step process of the reflex arc?

A
  1. When a stimulus is detected by receptors, impulses are sent along a sensory neurone to a relay neurone in the CNS.
  2. When the impulses reach a synapse between the sensory neurone and the relay neurone, they trigger chemicals to be released. These chemicals cause impulses to be sent along the relay neurone.
  3. When the impulses reach a synapse between the relay neurone and a motor neurone, the same thing happens. Chemicals are released and cause impulses to be sent along the motor neurone.
  4. The impulses then travel along the motor neurone to the effector (which is usually a muscle).
  5. If the effector is a muscle, it will respond to the impulse by contracting. If it’s a gland, it will secrete a hormone.
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31
Q

Why don’t reflexes require conscious thought?

A

Because the electrical impulses pass almost directly from the receptor to the effector.

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32
Q

What is a synapse?

A

The connection between 2 neurones is called a synapse.

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33
Q

How do synapses work?

A

The nerve signal is transferred by chemicals which diffuse across the synapse. These chemicals bind to receptors causing an impulse to travel down the next neurone.

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34
Q

What are the chemicals in synapses called?

A

Neurotransmitters.

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35
Q

What is the purpose of synapses?

A

Synapses slow down the transmission of a nervous impulse because the diffusion of chemicals across the gap takes time.

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36
Q

What is a 7 step worked through example of the response of a person to a bee stinging them?

A
  1. Bee stings finger.
  2. Stimulation of pain receptor.
  3. Impulses travel along sensory neurone.
  4. Impulses are passes along a relay neurone via a synapse through coordination centre.
  5. Impulses travel along a motor neurone, via a synapse.
  6. When impulses reach the muscle, it contracts.
  7. Hand moves away from source of the pain.
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37
Q

What is reaction time?

A

The time it takes to respond to a stimulus => often less that a second.

38
Q

What can reaction time be affected by?

A

Things like age, gender or drugs.

39
Q

What is the process for required practical 7, testing the effect of caffeine on reaction time? (6)

A
  1. The person being tested should sit with their arm resting on the edge of a table (this should stop them moving their arm up or down during the test).
  2. Hold a ruler vertically between their thumb and forefinger. Make sure that the zero end of the ruler is level with their thumb and finger. Then let go without giving any warning.
  3. The person being tested should try to catch the ruler as quickly as they can — as soon as they see it fall.
  4. Reaction time is measured by the number on the ruler where it’s caught, at the top of the thumb — the further down it’s caught (i.e. the higher the number), the slower their reaction time.
  5. Repeat the test several times then calculate the mean distance that the ruler fell.
  6. The person being tested should then have a caffeinated drink (e.g. 300 ml of cola. After ten minutes, repeat steps 1-5.
40
Q

What are the 4 control variables of required practical 7, testing the effect of caffeine on reaction time?

A
  • You should use the same person to catch the ruler each time.
  • That person should always use the same hand to catch the ruler.
  • The ruler should always be dropped from the same height.
  • You should make sure that the person being tested has not had any caffeine (or anything else that may affect their reaction time) before the start of the experiment.
41
Q

What are the 2 main safety issues of required practical 7, testing the effect of caffeine on reaction time?

A
  • Any drinks need to be consumed outside of the lab, away from chemicals/ hazards.
  • The person being tested should avoid drinking caffeine for the rest of the day, after experiment, to avoid unpleasant side-effects.
42
Q

How can using a computer to measure reaction time be more effective and precise? (3)

A
  • Removes the possibility of human error from the measurement.
  • Answer can be given in milliseconds => more accurate.
  • Removes the possibility that the person can predict when to respond. I.e, when using the ruler test, catcher may learn to anticipate the drop by reading tester’s body language.
43
Q

What is the brain/ what is it made up of/ what does it do?

A

The brain is made up of billions of interconnected neurones and is responsible for controlling all complex behaviours. Within the brain are different regions that carry out different functions.

44
Q

What are the 9 regions of the brain?

A
  • Pituitary gland
  • Cerebral Cortex
  • Brain stem
  • Medulla
  • Cerebellum
  • Frontal lobe
  • Temporal lobe
  • Parietal lobe
  • Occipital lobe
45
Q

What is the function of the pituitary gland?

A

Secretes several hormones into the blood in response to body conditions.

46
Q

What is the function of the cerebral cortex?

A

Important in conscious thought, language, memory and intelligence.

47
Q

What is the function of the medulla?

A

Controls unconscious activities such as heartbeat, movements of the gut, breathing, swallowing and regulation of body temperature.

48
Q

What is the function of the cerebellum?

A

Coordinates muscle activity, controls balance, gross and fine motor skills and hand-eye coordination.

49
Q

What is the function of the brain stem?

A

It regulates body temperature, heart rate, swallowing and breathing.

50
Q

How have the functions of the brain been discovered? (4)

A
  • Electrical stimulation of the brain
  • Animal studies
  • MRI, PET, CAT/CT and fMRI scans
  • Brain injuries
51
Q

How can studying patients with brain damage help discover functions of the brain? (2)

A
  • If a small part of the brain has been damaged, the effect this has on the patient can reveal lots about what the damaged part of the brain does.
  • E.g, if an area at the back of the brain was damaged by a stroke and the patient went blind, you know that the area has something to do with vision.
52
Q

How can electrically stimulating the brain help discover functions of the brain? (3)

A
  • The brain can be stimulated by pushing a tiny electrode into the tissue and giving it a small zap of electricity.
  • By observing what stimulating different parts of the brain does, it’s possible to get an idea of what those parts do.
  • E.g, when a certain part of the brain (the motor area) is stimulated, it causes muscle contraction and movement.
53
Q

How can MRI scans help discover functions of the brain? (2)

A
  • A magnetic resonance imaging (MRI) scanner is a big tube-like machine that can produce a very detailed picture of the brain’s structures.
  • Scientists use it to find out what areas of the brain are active when people are doing things like listening to music, or trying to recall a memory.
54
Q

What are the benefits of treatments for disorders of the nervous system using the brain and its studies? (2)

A
  • Electrical stimulation of the brain can help reduce muscle tremors caused by nervous system disorders such as Parkinson’s disease.
  • Surgery to remove a part of the brain that’s causing seizures can be an option to treat epilepsy if it can’t be controlled by medication.
55
Q

What are the risks of treatments for disorders of the nervous system using the brain and its studies? (3)

A
  • The brain is complex and delicate - investigations of brain function and any treatment of brain damage or disease is difficult.
  • Physical damage to the brain.
  • Increased problems with brain function, e.g. difficulties with speech.
56
Q

What is the cornea?

A

Transparent lens that refracts light as it enters the eye.

57
Q

What is the iris?

A

Controls how much light enters the pupil.

58
Q

What is the lens?

A

Transparent disc that can change shape to focus light on the retina.

59
Q

What is the retina?

A

Contains light receptor cells - rods (detect light intensity) and cones (detect colour).

60
Q

What is the optic nerve?

A

Sensory neurone that carries impulses between the eye and the brain.

61
Q

What is the pupil?

A

Hole that allows light to enter the eye.

62
Q

What is the sclera?

A

The tough, supporting wall of the eye.

63
Q

What are ciliary muscles and suspensory ligaments?

A

Control the shape of the lens.

64
Q

What can very bright light do to the retina?

A

Damage it.

65
Q

What happens to the eye in dim light? (4)

A
  • Radial muscles contract
  • Circular muscles relax
  • Pupil is wide
  • More light enters
66
Q

What is the acronym to remember what happens to the eye in dim light?

A
  • Romeo needs Candles
  • Radial muscles Contract (circular relax)
67
Q

What happens to the eye in bright light?

A
  • Radial muscles relax
  • Circular muscles contract
  • Pupil is narrow
  • Less light enters
68
Q

What is the acronym to remember what happens to the eye in bright light?

A
  • Romeo needs Ray-bans
  • Radial muscles Relax (circular contract)
69
Q

What is accommodation?

A

Accommodation is the process of changing the shape of the lens to focus on near or distant objects.

70
Q

How does accommodation work? (2)

A
  • The lens is elastic and its shape can be changed when the suspensory ligaments attached to it become tight or loose.
  • The changes are brought about by the contraction or relaxation of the ciliary muscles.
71
Q

What is the acronym for the effect of close objects on ciliary muscles?

A
  • Close Ciliary Contract
    (suspensory ligaments loosen)
72
Q

Look at diagram for close objects - accommodation.

A

Rate knowledge.

73
Q

What is the acronym for the effect of far objects on ciliary muscles?

A
  • Far Ciliary Relax
    (suspensory ligaments tighten)
74
Q

Look at diagram for far objects - accommodation.

A

Rate knowledge.

75
Q

What is myopia?

A

Short-sightedness.

76
Q

What is wrong with the eyeball with myopia?

A

Too elongated (distance between retina and lens is too great).

77
Q

What kind of glasses lens helps myopia?

A

Concave lens.

78
Q

Look at diagrams for myopia.

A

Rate knowledge.

79
Q

What is hyperopia?

A

Long-sightedness.

80
Q

What is wrong with the eyeball with hyperopia?

A

Too short (distance between retina and lens is too small).

81
Q

What kind of glasses lens helps hyperopia?

A

Convex lens.

82
Q

Look at diagrams for hyperopia.

A

Rate knowledge.

83
Q

How can hard and soft contact lenses be used to treat hyperopia and myopia? (3)

A
  • These sit on the surface of the eye and are almost invisible, making them ideal for activities like sports.
  • They are shaped to compensate for the fault in focusing.
  • Soft lenses are more comfortable but carry a higher infection risk than hard lenses.
84
Q

How can laser eye surgery be used to treat hyperopia and myopia? (4)

A
  • Lasers can be used to change the shape of the cornea (changing how it refracts light onto the retina).
  • However, like all surgical procedures there is a risk of unexpected damage occurring during the procedure which could lead to worse vision or an infection.
  • For myopia the cornea is slimmed down, reducing the refractive power.
  • For hyperopia the cornea is changed so the refractive power increases.
85
Q

How can replacement lens surgery be used to treat hyperopia and myopia? (3)

A
  • Sometimes hyperopia may be more effectively treated by replacing the lens of the eye instead of changing the shape of the cornea with laser eye surgery.
  • In replacement lens surgery, the natural lens of the eye is removed and an artificial lens, made of clear plastic, is inserted in its place.
  • As it involves work inside the eye, replacing a lens carries higher risks than laser eye surgery, including possible damage to the retina (could lead to loss of sight).
86
Q

What is the optimum body temperature for a human? Why?

A

37 degrees celsius, because this is the temperature that enzymes in the human body work best at.

87
Q

What is body temperature monitored and controlled by? (2)

A
  • The thermoregulatory centre in the brain.
  • A negative feedback system - if it gets too high or low, the body responds to bring the temperature back to the optimum.
88
Q

How does the thermoregulatory centre work? (2)

A
  • The thermoregulatory centre contains receptors sensitive to the temperature of the blood.
  • The skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre.
89
Q

What is the negative feedback loop for controlling an increase in body temperature? (4)

A
  • Temperature receptors in skin and thermoregulatory centre detect an increase in body temperature.
  • Nervous impulses sent to the thermoregulatory centre in the brain.
  • The thermoregulatory centre coordinates a response.
  • Vasodilation, sweat is produced, hairs lie flat on skin.
90
Q

What are the 3 responses that reduce core body temperature? (more detailed)

A
  • Hairs on the skin lie flat. This means less air is trapped near the surface of the skin, so there isn’t a layer of insulating air surrounding the skin. This allows heat to be transferred to the environment more easily.
  • Sweat is produced by sweat glands. When sweat evaporates from the skin, it transfers energy to the environment, helping to reduce body temperature.
  • The blood vessels supplying the skin capillaries dilate (get wider) so more blood flows close to the surface of the skin. This is called vasodilation. It helps transfer energy from the skin to the environment.
91
Q

What is the negative feedback loop for controlling a decrease in body temperature? (4)

A
  • Temperature receptors in skin and thermoregulatory centre detect a decrease in body temperature.
  • Nervous impulses sent to the thermoregulatory centre in the brain.
  • The thermoregulatory centre coordinates a response.
  • Vasoconstriction, sweating stops, shivering, hairs stand up on skin.
92
Q

What are the 4 responses that increase core body temperature? (more detailed)

A
  • Hairs on the skin stand up. This traps an insulating layer of air next to the skin, reducing the amount of energy transferred to the environment.
  • No sweat is produced.
  • Blood vessels supplying skin capillaries constrict (get narrower) to reduce the skin’s blood supply. This is called vasoconstriction. It reduces the amount of blood that flows close to the surface of the skin and so less energy is transferred from the skin to the environment.
  • When you’re cold you shiver (your muscles contract automatically). This needs respiration, which transfers some energy to warm the body.

GCSE Biology (8 decks)

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